Mechanisms and kinetics of non-isothermal polymerization of N,N'-bismaleimide-4,4'-diphenylmethane (BMI) with 1,3-dimethylbarbituric acid (13BTA) were investigated. Competition between free radical polymerization and Michael addition reaction mechanisms for the BMI/13BTA reaction system was characterized by using DSC and H-1 NMR technique. Model-free (isoconversional) method was used to determine triplet kinetic parameters for the polymerization of BMI with 13BTA. Average activation energy (E alpha) and pre-exponential factor (A alpha) are ca. 56 kJ mol(-1) and 65.83 x 10(5) min(-1) in the fractional conversion (a) range 0.1-0.9, respectively. Particle nucleation involved in the polymerization process was satisfactorily predicted by the nucleation Avrami-Erofeev model {f(alpha) = n(1- alpha)[-ln(1 - alpha)]((n - 1/n)} with n = 1.46. The z-average particle size of microgel particles was measured by dynamic light scattering, which supported the particle nucleation and growth process.